This invention relates to an ink fountain device for continuously discharging printing ink in an ink fountain at a constant rate.
The ink fountain device for supplying printing ink to a printing plate mounted on the plate cylinder for a rotary printing press including an ink fountain roller, for discharging the printing ink in an ink fountain at a predetermined rate, and a plurality of groups of rollers which distribute and uniformly smooth the discharged ink. An ink film is then transferred to the surface of the printing plate. The ink fountain is defined by an ink fountain roller supported by opposite side frames, and a fountain blade made of a thin steel plate and secured to a support with its front edge in abutment with the periphery of the fountain roller. The printing ink stored in the ink fountain flows out as a thin ink film through a narrow gap formed between the periphery of the fountain roller and the fountain blade. A plurality of adjusting screws are threaded through the support at a spacing of about 20 to 50 mm. The inner ends of the adjusting screws engage the fountain blade so that when the adjusting screws are independently reciprocated the gap between the fountain blade and the fountain roller is varied so as to adjust the quantity of ink in respective sections divided in the axial direction of the fountain roller, that is in the axial direction of the plate cylinder, thus enabling adjustment of the quantity of ink in accordance with a tone of an image on the printing plate.
In an ink fountain device constructed as above described, however, since the fountain blade is made of a single continuous plate, where it is desired to decrease the quantity of the ink at portions corresponding to two spaced apart adjusting screws and to increase the quantity of the ink at a portion corresponding to an adjusting screw located between the two spaced apart adjusting screws, even when the central adjusting screw is retracted while the two spaced adjusting screws are maintained in their forward positions, the fountain blade would not respond to the adjustment of the central adjusting screw but maintained its state deformed by the two outside adjusting screws. For this reason, it was necessary to slightly retract the adjusting screws on both sides which resulted in a rough adjustment. Furthermore, when one screw is advanced, screws on both sides thereof are influenced, preventing a correct adjustment.
To eliminate this disadvantage, a divided blade type fountain device has been proposed in which the fountain blade is divided into a plurality of sections along the axis of the fountain roller so that the respective blade sections can be independently adjusted. With this construction, however, as the blade is divided into a plurality of sections, the ink permeates into the sliding surfaces between the support and the blade sections and further into the gap adjusting member through gaps between the divided blade sections, such ink rendering it impossible to finely adjust the quantity of the ink to be fed due to ink sludge or to move the divided sections. Furthermore, when the color of the ink is and the used ink remains, the used ink and the new ink are mixed. Accordingly, it was necessary to completely remove the used ink, thus requiring complicated maintenance.